Safety starting crank



Elm warrior, .TM i fake? Z May 19, 1925.

, L. T. MITCHELL SAFETY swm'rme 0mm:

Filed May 12 1924 Patented May 19, 1925.

PATENT OFFlCE.

LOUIE T. MITCHELL, 0F LICKING, MISSOURI.

SAFETY sTAR'rING CRANK.

Application filed May 12,

To all whom it may concern Be it known that I, LOUlE T. MITCHELL, State of Missouri, county of Texas, a citizen of the United States, residing at Licking, in the county of Texas and State of Missouri, have invented certain new and useful Improvements in Safety Starting Cranks; and I do hereby declare the following to be a full, clear, and exact description of the in vention, such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to starting cranks for internal combustion engines and aims to provide a device ofthis nature which will prevent injury in the event of back fire or premature explosion tending to throw the crank backward when starting the engine.

In accordance with the present invention, the crank is automatically advanced to operative position when turned forwardly and is automatically thrown outwardly in the event of the engine firing backwardly, thereby disconnecting the crank and preventing any possible injury to the one throwing the engine over in an attempt to start the same.

Other objects and advantages will be apparent and suggest themselves as the nature of the invention is understood.

Vhile the drawing illustrates an embodiment of the invention it is to be understood that in adapting the same to meet different conditions and requirements, various changes in the form, proportion and minor details of construction may be resorted to without departing from the spirit of the invention.

Referring to the accompanying drawing forming a part of the application Figure 1 is a side view of a safety starting crank embodying the invention;

Figure 2 is a top plan view thereof;

Figure 3 is a detail longitudinal sectional view thereof;

Figure 4 is a detail cross section on the line 44 of Figure 2, looking in the direction of the arrows; and

Figure 5 is a fragmentary view showing more clearly the bearing, the extensions thereof, and the collar having a projection adapted to co-act with the extensions of the bearing and limit the counter-clockwise movement of the crank when moved outward.

Corresponding and like parts are referred 1924. Serial No. 712,802.

to in the following description and designated in the several views of the drawing by like reference characters.

The starting crank comprises the usual shaft 1, arm 2 and treadle 3 and is mounted in the usual way so as to receive both a longitudinal and a rotary movement, the longitudinal movement being essential to couple the crank to the engine shaft when throwing the engine over in the starting thereof. The numeral 4 designates a supporting member which is provided with a bearing 5 in which the starting crankis. mounted in a well known manner. In accordance with the present invention the bearing 5 has an extension in which is formed a helical or spiral slot Gwhich is closed at opposite ends a pin 7 forming the closure for the outer end of the slot.

prevent a casualty in the event of the engine back firing or prematurely starting in a backward direction. The collar 8 is provided with a projection 9 which operates in the spiral or helical slot 6 and is formed with a projection 10 which forms a stop to engage the extension 11 of the bearing 5 and limit the counter-clockwise movement of the crank. A pin 12 inserted in an opening of the shaft 1 limits the outward movement thereof by engaging the inner end of .1

the bearing 5. The eye or opening of the collar 8 is provided with ratchet teeth 13 which cooperate with a spring actuated dog 14 whereby the shaft 1 and collar 8 become locked when the starting crank receives a counter-clockwise movement and when this occurs the projection 9 riding in the helical or spiral slot 6 moves the crank outward and automatically disconnects it from the shaft of the engine before any possible injury can occur.

What is claimed is 1. A safety starting crank for an internal combustion engine, the same comprising a collar loosely mounted upon the shaft of the crank and ln'iving a ratchet connection therewith and provided with a projection, a

bearing for said shaft having a helical guide co-acting with said projection to effect an outward movement of the crank when the latter receives a counter-clockwise movement whereby to automatically disconnect it from the shaft of the engine.

2. A safety starting crank, a. collar loosely mounted upon the shaft thereof and having a ratchet connection therewith and provided with twin offstanding projections, the one constituting a stop, a helical. guide coracting with the other projection to effect an outward movement of the crank and automatic disconnecting thereof from the, shaft of the engine when the latter back fires, and a hearing for said shaft having an extension adapted to co-act With the said stop to limit he movement of the crank when automatically disconnected from the shaft of the engine,

3. In a safety starting crank, a bearing for the, shaft ofsaid crank having an extension in which is formed a helical slot, a collar loosely mounted upon the shaftof the crank and having a ratchet connection therewith and formed with offstanding projections, the one operating in the helical slot and the other forming a stop to limit the outer clockwise movement of the crank when the engine back fires.

l. In a safety starting crank, a relatively fixed bearing for the shaft of said crank otherv operating in the helical slot, and a pin mounted in the shaft of the crank and adapted to engage the bearing and limit the outward movement of the crank when un coupled from the shaft of the engine.

In testimony whereof I affix my signature in presence of two witnesses.

LOUIE T. MITCHELL. lVitnesses C. L. JOHNSON, O. A. JOHNSON. 

